Aminoaromatic ester polylactone aminocarbamates and fuel compositions containing the same

ABSTRACT

Aminoaromatic ester polylactone aminocarbamates having the formula: ##STR1## wherein R 1  is an alkyl group having from 1 to about 100 carbon atoms or an aralkyl or alkaryl group having from 7 to about 100 carbon atoms; 
     R 2  is an alkylene group of about 2 to 5 carbon atoms; 
     A is a polyamine moiety having at least one basic nitrogen atom; 
     x is an integer from 1 to 25; 
     and y is an integer from 0 to 6. The aminoaromatic ester polylactone aminocarbamates of formula I are useful as fuel additives for the prevention and control of engine deposits.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from U.S. Provisional application Ser. No. 60/000,929, filed Jul. 6, 1995.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to novel end-functionalized polylactones. More particularly, this invention relates to novel aminoaromatic ester polylactone aminocarbamates and their use in fuel compositions to prevent and control engine deposits.

2. Description of the Related Art

It is well known that automobile engines tend to form deposits on the surface of engine components, such as carburetor ports, throttle bodies, fuel injectors, intake ports and intake valves, due to the oxidation and polymerization of hydrocarbon fuel. These deposits, even when present in relatively minor amounts, often cause noticeable driveability problems, such as stalling and poor acceleration. Moreover, engine deposits can significantly increase an automobile's fuel consumption and production of exhaust pollutants. Therefore, the development of effective fuel detergents or "deposit control" additives to prevent or control such deposits is of considerable importance and numerous such materials are known in the art.

For example, polyether amine fuel additives are well known in the art for the prevention and control of engine deposits. These polyether additives have a poly(oxyalkylene) "backbone", i.e., the polyether portion of the molecule consists of repeating oxyalkylene units. U.S. Pat. No. 4,191,537, issued Mar. 4, 1980 to R. A. Lewis et al., for example, discloses a fuel composition comprising a major portion of hydrocarbons boiling in the gasoline range and from 30 to 2,000 ppm of a hydrocarbyl poly(oxyalkylene) aminocarbamate having a molecular weight from about 600 to 10,000, and at least one basic nitrogen atom. The hydrocarbyl poly(oxyalkylene) moiety is composed of oxyalkylene units having from 2 to 5 carbon atoms in each oxyalkylene unit. These fuel compositions are taught to maintain the cleanliness of intake systems without contributing to combustion chamber deposits.

Poly(vinyl ether) amine fuel additives are also known in the art. For example, U.S. Pat. No. 5,306,314 discloses poly(vinyl ether) aminocarbamate fuel additives having a vinyl ether polymer backbone consisting of repeating vinyl ether units. These compounds are taught to be useful in fuel compositions to prevent and control engine deposits.

Polylactone polymer compositions have also been reported in the art. For example, U.S. Pat. No. 5,028,667 to McLain et al., discloses a process for the ring-opening polymerization of lactones using as catalysts compounds of yttrium and the rare earth metals. This patent further teaches that the resulting polylactone polymers are useful as biodegradable polymers for medical uses and as flexible films for packaging.

P. Dubois et al., in Macromolecules, 1992, Volume 25, Pages 2614-2618, describe the ring-opening polymerization of caprolactone initiated by primary amines and trialkylaluminum. The resulting polycaprolactone is taught to be useful in the biomedical field due to its high permeability, lack of toxicity for living organisms, biodegradability and capacity to be blended with various commercial polymers over a wide composition range.

D. Tian et al., in Macromolecules, 1994, Volume 27, Pages 4134-4144, describe star-branched polycaprolactone polymers having primary amine end groups. These polymers are prepared by the ring-opening polymerization of caprolactone with aluminum alkoxides and a trimesic acid trichloride termination agent.

U.S. Pat. No. 4,820,432 to Lundberg et al. discloses poly (C₅ to C₉ lactone) modified Mannich base adducts which are prepared by reacting a C₅ to C₉ lactone, an amine, an aldehyde, an N-hydroxyarylamine, and a hydrocarbyl substituted C₄ to C₁₀ monounsaturated dicarboxylic acid producing material, such as a polyisobutenyl succinic anhydride. These modified Mannich base adducts may be prepared, for example, by first reacting an N-hydroxyarylamine with a hydrocarbyl substituted dicarboxylic acid producing material to form an N-hydroxyaryl hydrocarbyl substituted imide, which is subsequently reacted with an aldehyde and an amine to form an intermediate Mannich base adduct having an amino functional group capable of initiating lactone ring opening polymerization, and then reacting the intermediate Mannich base adduct with a C₅ to C₉ lactone. This patent further teaches that the resulting poly (C₅ to C₉ lactone) modified Mannich base adduct is useful as an oil soluble dispersant additive for fuel and lubricating oil compositions.

It has now been discovered that certain polylactone aminocarbamates provide excellent control of engine deposits, especially intake valve deposits, when employed as fuel additives in fuel compositions.

SUMMARY OF THE INVENTION

The present invention provides novel fuel-soluble. aminoaromatic ester polylactone aminocarbamate fuel additives which are useful for the prevention and control of engine deposits, particularly intake valve deposits.

The fuel-soluble aminoaromatic ester polylactone aminocarbamates of the present invention have the formula: ##STR2## wherein R₁ is an alkyl group having from 1 to about 100 carbon atoms or an aralkyl or alkaryl group having from 7 to about 100 carbon atoms;

R₂ is an alkylene group of about 2 to 5 carbon atoms;

A is a polyamine moiety having at least one basic nitrogen atom;

X is an integer from 1 to 25;

and y is an integer from 0 to 6.

The present invention further provides a fuel composition comprising a major amount of hydrocarbons boiling in the gasoline or diesel range and an effective deposit-controlling amount of an aminoaromatic ester polylactone aminocarbamate of the present invention.

The present invention additionally provides a fuel concentrate comprising an inert stable oleophilic organic solvent boiling in the range of from about 150° F. to 400° F. (about 65° C. to 205° C.) and from about 10 to 70 weight percent of an aminoaromatic ester polylactone aminocarbamate of the present invention.

Among other factors, the present invention is based on the surprising discovery that certain aminoaromatic ester polylactone aminocarbamates provide excellent control of engine deposits, especially on intake valves, when employed as fuel additives in fuel compositions.

DETAILED DESCRIPTION OF THE INVENTION

The fuel additives provided by the present invention have the general formula: ##STR3## wherein A, R₁, R₂, x and y are as defined hereinabove.

A is preferably a polyamine moiety containing 2 to about 12 amine nitrogen atoms and from 2 to about 40 carbon atoms. More preferably, A is a polyamine moiety derived from a polyalkylene polyamine containing 2 to about 12 nitrogen atoms and 2 to about 24 carbon atoms. Still more preferably, A is a polyamine moiety derived from a polyalkylene polyamine having the formula:

    H.sub.2 N--(R.sub.3 NH).sub.z --H

wherein R₃ is an alkylene group having 2 to about 6 carbon atoms and z is an integer from 1 to 4. Most preferably, A is a polyamine moiety derived from ethylene diamine or diethylene triamine.

Preferably, R₁ is an alkyl group having from 1 to about 100 carbon atoms. More preferably, R₁ is an alkyl group having about 3 to about 100 carbon atoms. In a particularly preferred embodiment of the present invention, R₁ is a polyisobutyl group having about 8 to about 100 carbon atoms.

R₂ is preferably an alkylene group having 4 to 5 carbon atoms. More preferably, R₂ is an alkylene group having 5 carbon atoms.

Preferably, x is an integer from 1 to 10. More preferably, x is an integer from 1 to 5. Preferably, y is an integer from 0 to 2. More preferably, y is 0.

A preferred group of aminoaromatic ester polylactone aminocarbamates are those of formula I wherein A is derived from a polyalkylene polyamine containing 2 to about 12 nitrogen atoms and 2 to about 24 carbon atoms; R₁ is alkyl having 1 to about 100 carbon atoms; R₂ is alkylene having 4 to 5 carbon atoms; and x is an integer from 1 to 10; and y is an integer from 0 to 2.

It is also preferred that the amine substituent on the aminoaromatic ester moiety of the polylactone compounds of this invention be situated in a meta or para position relative to the ester moiety on the aromatic ring. It is particularly preferred that the amine substituent be situated in a para position relative to the ester moiety on the aromatic ring.

The polylactone aminocarbamates of the present invention will generally have a sufficient molecular weight so as to be non-volatile at normal engine intake valve operating temperatures. Typically, the molecular weight of the polylactone aminocarbamates of this invention will range from about 300 to about 5,000, preferably from about 300 to about 3,000.

Definitions

As used herein the following terms have the following meanings unless expressly stated to the contrary.

The term "alkyl" refers to both straight- and branched-chain alkyl groups.

The term "alkylene" refers to straight- and branched-chain alkylene groups having at least 2 carbon atoms. Typical alkylene groups include, for example, ethylene (--CH₂ CH₂ --), propylene (--CH₂ CH₂ CH₂ --), isopropylene (--CH(CH₃)CH₂ --), n-butylene (--CH₂ CH₂ CH₂ --), sec-butylene (--CH(CH₂ CH₃)CH₂ --), n-pentylene (--CH₂ CH₂ CH₂ CH₂ CH₂), and the like.

The term "polylactone" refers to a ring-opened lactone polymer having the general formula: ##STR4## wherein R₂ is an alkylene group of 2 to 5 carbon atoms and x is an integer from about 1 to about 25. The term "lactone unit" refers to one monomeric unit of a polylactone polymer. Such polylactone polymers are obtained by the ring-opening polymerization of a lactone. When referring herein to the number of lactone units in a polylactone compound, it is to be understood that this number refers to the average number of lactone units in such compounds unless expressly stated to the contrary.

Also, for purposes of the present invention, the term "polylactone" is meant to include those ring-opened compounds having only about 1 lactone unit, that is, those compounds wherein x is about 1.

General Synthetic Procedures

The aminoaromatic ester polylactone aminocarbamates of this

invention may be prepared by the following general methods and procedures. It should be appreciated that where typical or preferred process conditions (e.g. reaction temperatures, times, mole ratios of reactants, solvents, pressures, etc.) are given, other process conditions may also be used unless otherwise stated. Optimum reaction conditions may vary with the particular reactants or solvents used, but such conditions can be determined by one skilled in the art by routine optimization procedures.

Moreover, those skilled in the art will recognize that it may be necessary to block or protect certain functional groups while conducting the following synthetic procedures. In such cases, the protecting group will serve to protect the functional group from undesired reactions or to block its undesired reaction with other functional groups or with the reagents used to carry out the desired chemical transformations. The proper choice of a protecting group for a particular functional group will be readily apparent to one skilled in the art. Various protecting groups and their introduction and removal are described, for example, in T. W. Greene and P. G. M. Wuts, Protective Groups in Organic Synthesis, Second Edition, Wiley, New York, 1991, and references cited therein.

In the present synthetic procedures, amino groups may require protection and this may be accomplished by employing a standard amino protecting group, such as a benzyloxycarbonyl or a trifluoroacetyl group. Additionally, as will be discussed in further detail hereinbelow, the aminoaromatic esters employed in this invention having an amino group on the aromatic moiety will generally be prepared from the corresponding nitro derivative. Accordingly, in many of the following procedures, a nitro group will serve as a protecting group for the amino moiety.

The aminoaromatic ester polylactone aminocarbamates of the present invention contain (a) an aminoaromatic ester component, (b) a polylactone component, and (c) an amine component which is covalently linked to the polylactone component through a carbamate connecting group.

A. The Aminoaromatic Ester Component

The aminoaromatic esters employed to make the polylactone aminocarbamates of the present invention have the following formula: ##STR5## wherein R₁ and y are as defined above. These compounds may be prepared by esterifying an aromatic carboxylic acid having the formula: ##STR6## wherein W is amino or an amino protecting group, such as nitro, and y is as defined above, with a monohydroxy alcohol having the formula:

    R.sub.1 --OH                                               (V)

wherein R₁ is as defined above, using conventional esterification reaction conditions.

The aromatic carboxylic acids of formula IV are either known compounds or can be prepared from known compounds by conventional procedures. Representative aromatic carboxylic acids suitable for use as starting materials include, for example, 2-aminobenzoic acid (anthranilic acid), 3-aminobenzoic acid, 4-aminobenzoic acid, 2-aminophenylacetic acid, 3-aminophenylacetic acid, 4-aminophenylacetic acid, 2-nitrobenzoic acid, 3-nitrobenzoic acid, 4-nitrobenzoic acid, 2-nitrophenylacetic acid, 3-nitrophenylacetic acid, 4-nitrophenylacetic acid, and the like.

Preferred aromatic carboxylic acids include 3-aminobenzoic acid, 4-aminobenzoic acid, 3-nitrobenzoic acid, and 4-nitrobenzoic acid.

The aromatic carboxylic acids of formula IV are esterified with a monohydroxy alcohol of formula V, that is, R₁ OH, wherein R₁ is an alkyl group having 1 to about 100 carbon atoms, or an aralkyl or alkaryl group having 7 to about 100 carbon atoms.

Suitable monohydroxy alcohols include straight or branched chain alkyl alcohols having i to about 100 carbon atoms, preferably about 3 to about 100 carbon atoms, or a straight or branched chain aralkyl or alkaryl alcohol containing about 7 to about 100 carbon atoms. Preferred alkaryl alcohols include alkylphenols having from 7 to about 100 carbon atoms. Preferred aralkyl alcohols include phenyl-substituted alkanols having from 7 to about 100 carbon atoms.

Preferred straight-chain alcohols have about 3 to about 30 carbon atoms and include, for example, n-propanol, n-butanol, n-pentanol, n-hexanol, n-heptanol, octanol, nonanol, decanol, hexadecanol (cetyl alcohol), octadecanol (stearyl alcohol) and the like.

Preferred branched-chain alcohols include C₃ to C₃₀ alcohols such as iso-propanol, sec-butanol, iso-butanol, 3,5,5, -trimethyl hexanol, and the like.

Preferred branched-chain alcohols also include those derived from polymers of C₂ to C₆ olefins, such as alcohols derived from polypropylene and polybutene. Particularly preferred are polypropylene alcohols having 9 to about 60 carbon atoms and polybutene alcohols having 8 to about 100 carbon atoms. Alcohols derived from the alpha olefin oligomers of C₈ to C₁₆ alpha olefins, such as the dimer, trimer and tetramer of decene as described in U.S. Pat. No. 4,045,508, issued Aug. 30, 1977 to B. L. Cupples et al., are also useful in this invention.

Many of these straight- and branched-chain alcohols are commercially available and the others can be readily prepared from the corresponding olefins by conventional procedures. Suitable procedures for preparing alcohols from olefins are described for example in I. T. Harrison and S. Harrison, Compendium of Organic Synthetic Methods, pp. 119-122, Wiley-Interscience, New York (1971) and references cited therein, as well as in U.S. Pat. Nos. 5,055,607 and 4,859,210.

As indicated above, the aminoaromatic esters of formula III may be prepared by esterifying an aromatic carboxylic acid of formula IV with an alcohol of formula V under conventional esterification reaction conditions.

Typically, this reaction will be conducted by contacting an alcohol of formula V with about 0.25 to about 1.5 molar equivalents of an aromatic carboxylic acid of formula IV in the presence of an acidic catalyst at a temperature in the range of about 70° C. to about 160° C. for about 0.5 to about 48 hours. Suitable acid catalysts for this reaction include p-toluene sulfonic acid, methanesulfonic acid and the like. The reaction may be conducted in the presence or absence of an inert solvent, such as benzene, toluene and the like. The water generated by this reaction is preferably removed during the course of the reaction by, for example, azeotropic distillation with an inert solvent, such as toluene.

Alternatively, the aminoaromatic esters of formula III may be prepared by reacting an alcohol of formula V with an acid halide derived from an aromatic carboxylic acid of formula IV, such as an acid chloride or acid bromide.

Generally, the carboxylic acid moiety of formula IV may be converted into an acyl halide moiety by contacting a compound of formula IV with an inorganic acid halide, such as thionyl chloride, phosphorous trichloride, phosphorous tribromide, or phosphorous pentachloride; or with oxalyl chloride. Typically, this reaction will be conducted using about 1 to 5 molar equivalents of the inorganic acid halide or oxalyl chloride, either neat or in an inert solvent, such as diethyl ether, at a temperature in the range of about 20° C. to about 80° C. for about 1 to about 48 hours. A catalyst, such as N,N-dimethylformamide, may also be used in this reaction.

Reaction of the acid halide derived from formula IV with an alcohol of formula V provides an aromatic ester of formula III. Typically, this reaction is conducted by contacting the alcohol of formula V with about 0.9 to about 1.5 molar equivalents of the acid halide in an inert solvent, such as toluene, dichloromethane, diethyl ether, and the like, at a temperature in the range of about 25° C. to about 150° C. The reaction is generally complete in about 0.5 to about 48 hours. Preferably, the reaction is conducted in the presence of a sufficient amount of an amine capable of neutralizing the acid generated during the reaction, such as triethylamine, di(isopropyl)ethylamine, pyridine or 4-dimethylaminopyridine.

When synthesizing the aminoaromatic esters of formula III, it is generally desirable to first prepare the corresponding nitro compound using the above-described synthetic procedures, and then to reduce the nitro group to an amino group using conventional procedures. Aromatic nitro groups may be reduced to amino groups using a number of procedures that are well known in the art. For example, aromatic nitro groups may be reduced under catalytic hydrogenation conditions; or by using a reducing metal, such as zinc, tin, iron and the like, in the presence of an acid, such as dilute hydrochloric acid.

Generally, reduction of the nitro group by catalytic hydrogenation is preferred. Typically, this reaction is conducted using about 1 to 4 atmospheres of hydrogen and a platinum or palladium catalyst, such as palladium on carbon. The reaction is typically carried out at a temperature of about 0° C. to about 100° C. for about 1 to 24 hours in an inert solvent, such as ethanol, ethyl acetate and the like. Hydrogenation of aromatic nitro groups is discussed in further detail in, for example, P. N. Rylander, Catalytic Hydrogenation in Organic Synthesis, pp. 113-137, Academic Press (1979); and Organic Synthesis, Collective Vol. I, Second Edition, pp. 240-241, John Wiley & Sons, Inc. (1941); and references cited therein.

B. The Polylactone Component

The polylactone component of the polylactone aminocarbamates of the present invention is an aminoaromatic ester-substituted lactone polymer containing about 1 to about 25 lactone units. Generally, the polylactone component will have an aminoaromatic ester-substituted lactone unit at one end of the lactone polymer and will be terminated with a hydroxyl group at the other end of the lactone polymer.

The polylactone component of the polylactone aminocarbamates of this invention is preferably prepared by polymerizing certain lactone monomers under "living polymerization" conditions. The term "living polymerization" is well known in the art and refers to polymerization reactions which occur in the substantial absence of chain transfer and termination reactions. Under such conditions, the reactive end of the growing polymer is essentially stable indefinitely. Accordingly, each lactone monomer can be added sequentially to the growing polylactone chain in a controlled step-by-step manner. Thus, living polymerization allows polylactones to be prepared having a substantially predictable sequence of lactone units.

In general, the polylactone polymer may be prepared by first reacting an aminoaromatic ester of the formula: ##STR7## wherein R₁ and y are as defined above, with a suitable lactone polymerization catalyst, such as trialkylaluminum, to form a polymerization initiator which is subsequently reacted with a lactone of the formula: ##STR8## wherein R₂ is as defined above, to provide the desired aminoaromatic ester-substituted polylactone having the formula: ##STR9## wherein R₁, R₂, x and y are as defined above.

For example, when employing trimethylaluminum as the polymerization catalyst, the reaction sequence may be described as follows: ##STR10##

As noted above, the aminoaromatic ester of formula III is reacted with a lactone polymerization catalyst to form a polymerization initiator. Suitable lactone polymerization catalysts include alkali and alkaline earth metal hydrides, alkoxides and alkyls; alkyl aluminum and alkyl zinc compounds; alkoxides of aluminum, titanium, zirconium and tin; yttrium and rare earth metal alkoxides; and the like.

Preferred polymerization catalysts for use with the aminoaromatic ester are the trialkylaluminum catalysts, such as trimethylaluminum and triethylaluminum.

Generally, the reaction of aminoaromatic ester with the polymerization catalyst will be conducted in a substantially anhydrous inert solvent at a temperature of about -50° C. to about 150° C., preferably -10° C. to 50° C. Suitable inert solvents include benzene, toluene, dichloromethane, diethyl ether and the like. Preferably, the reaction will be conducted under a dry inert gas atmosphere, such as nitrogen or argon, at about atmospheric or ambient pressure. Typically, the molar ratio of aminoaromatic ester to polymerization catalyst will range from about 0.5:1 to 5:1.

In the second stage of the polymerization process, the reaction product of the aminoaromatic ester and the polymerization catalyst, such as the amine-catalyst adduct of formula VIII, is reacted with a lactone monomer of formula VI. In this reaction the amine-catalyst adduct functions as an initiator for the lactone polymerization.

Suitable lactone monomers for use in the present invention include simple lactones containing from 3 to 6 carbon atoms, such as β-propiolactone, α-methyl-β-propiolactone, β-methyl-β-propiolactone, β-butyrolactone, γ-butyrolactone, γ-valerolactone, δ-valerolactone, δ-caprolactone, ε-caprolactone, and the like. Preferred lactone monomers include ε-valerolactone and ε-caprolactone. An especially preferred lactone monomer is ε-caprolactone.

Typically, the living polymerization reaction will be conducted in a substantially anhydrous inert solvent which may be the same or different than the solvent employed in forming the polymerization initiator. The polymerization reaction temperature will generally be in the range of about -50° C. to 150° C., preferably from about -10° C. to 50° C. Generally, the polymerization reaction will be carried out under a dry, inert gas atmosphere, such as nitrogen or argon, at about atmospheric or ambient pressure.

The molar ratio of lactone monomer to the polymerization initiator, such as the adduct of formula VIII, will generally range from about 1:1 to 25:1, preferably from about 1:1 to 10:1, and more preferably from about 1:1 to 5:1.

The time employed for the polymerization reaction can vary over a wide range and will depend to some extent on the reaction temperature and on the lactone monomers used in the polymerization process. Generally, the reaction will be conducted for about 0.05 to about 20 hours, preferably 0.05 to 1.0 hour or until essentially all the lactone monomers have reacted to form polymer.

When essentially all of the lactone monomer has reacted to form the polymer, the reactive terminal end of the polymer is quenched by contacting the reaction mixture with about 1 to about 100 equivalents of an aqueous acid solution, such as aqueous hydrochloric acid. This affords a hydroxy-terminated polylactone of formula VII.

The living polymerization of lactones is well known in the art and is further described, for example, in P. Dubois et al., Macromolecules, 1992, Vol. 25, Pages 2614-2618; D. Tian et al., Macromolecules, 1994, Vol. 27, Pages 4134-4144; and K. J. Ivin and T. Saegusa, Ring-Opening Polymerization, Vol. 1, Chapter 7, Elsevier, London, 1984, and references cited therein.

The hydroxy-terminated polylactone of formula VII may then be coupled with a suitable amine component using phosgene or a phosgene equivalent as described in further detail below.

C. The Amine Component

As indicated above, the polylactone aminocarbamates of the present invention contain an amine component which is covalently linked to the aforementioned polylactone component through a carbamate connecting group.

In general, the amine component will contain an average of at least about one basic nitrogen atom per molecule. A "basic nitrogen atom" is one that is titratable by a strong acid, for example, a primary, secondary or tertiary amine nitrogen; as distinguished from, for example, an carbamyl nitrogen, e.g. --OC(O)NH--, which is not titratable with a strong acid. Preferably, at least one of the basic nitrogen atoms of the amine component will be primary or secondary amine nitrogen, more preferably at least one will be a primary amine nitrogen.

The amine component of the polylactone aminocarbamates of this invention is preferably derived from a polyamine containing 2 to about 12 amine nitrogen atoms and from 2 to about 40 carbon atoms. Polyamines having a carbon-to-nitrogen ratio of from about 1:1 to 10:1 are particularly preferred.

In preparing the compounds of this invention using a polyamine where the various nitrogen atoms of the polyamine are not geometrically equivalent, several substitutional isomers are possible and each of these possible isomers is encompassed within this invention.

Suitable polyamines can have a straight- or branched-chain structure and may be cyclic or acyclic or combinations thereof. Generally, the amine nitrogen atoms of such polyamines will be separated from one another by at least two carbon atoms, i.e. polyamines having an aminal structure are not suitable. The polyamine may also contain one or more oxygen atoms, typically present as an ether or a hydroxyl group.

A particularly preferred group of polyamines for use in the present invention are polyalkylene polyamines, including alkylene diamines. Such polyalkylene polyamines will typically contain 2 to about 12 nitrogen atoms and 2 to about 24 carbon atoms. Preferably, the alkylene groups of such polyalkylene polyamines will contain from 2 to about 6 carbon atoms, more preferably from 2 to 4 carbon atoms.

Examples of suitable polyalkylene polyamines include ethylenediamine, propylenediamine, isopropylenediamine, butylenediamine, pentylenediamine, hexylenediamine, diethylenetriamine, dipropylenetriamine, diisopropylenetriamine, dibutylenetriamine, di-sec-butylenetriamine, triethylenetetraamine, tripropylenetetraamine, triisobutylenetetraamine, tetraethylenepentamine, pentaethylenehexamine, dimethylaminopropylamine and mixtures thereof.

Particularly suitable polyalkylene polyamines are those having the formula:

    H.sub.2 N--(R.sub.3 NH).sub.z --H                          (IX)

wherein R₃ is a straight- or branched-chain alkylene group having 2 to about 6 carbon atoms, preferably 2 to 4 carbon

atoms, most preferably 2 carbon atoms, i.e. ethylene (--CH₂ CH₂ --); and z is an integer from 1 to 4, preferably 1 or 2.

Particularly preferred polyalkylene polyamines are ethylenediamine, diethylenetriamine, triethylenetetraamine and tetraethylenepentamine. Most preferred are ethylenediamine and diethylenetriamine, especially ethylenediamine.

Also contemplated for use in the present invention are cyclic polyamines having one or more 5- to 6-membered rings. Such cyclic polyamines compounds include piperazine, 2-methylpiperazine, N-(2-aminoethyl)piperazine, N-(2-hydroxyethyl)piperazine, 1,2-bis-(N-piperazinyl)ethane, 3-aminopyrrolidine, N-(2-aminoethyl)pyrrolidine and the like. Among the cyclic polyamines, the piperazines are preferred.

Many of the polyamines suitable for use in the present invention are commercially available and others many be prepared by methods which are well known in the art. For example, methods for preparing amines and their reactions are detailed in Sidgewick's "The Organic Chemistry of Nitrogen", Clarendon Press, Oxford, 1966; Noller's "Chemistry of Organic Compounds", Saunders, Philadelphia, 2nd Ed., 1957; and Kirk-Othmer's "Encyclopedia of Chemical Technology" 2nd Ed. especially Volume 2, pp 99-116.

D. The Carbamate Connecting Group

The carbamate connecting group which covalently links the polylactone component to the amine component has the formula: ##STR11## wherein the ether oxygen may be regarded as being derived from the hydroxyl group of a hydroxy-terminated polylactone of formula VII; and the nitrogen atom may be regarded as being derived from a nitrogen atom of a suitable amine component. The carbonyl group, --C(O)--, is preferably provided by a carbonyl-containing coupling agent, such as phosgene or a phosgene equivalent. Economically, phosgene is the preferred coupling agent. Alternatively, suitable phosgene equivalents include, for example, 1,1'-carbonyldiimidazole, trichloromethyl chloroformate (diphosgene) and bis(trichloromethyl) carbonate (triphosgene).

The polylactone aminocarbamates of the present invention. are preferably prepared, for example, by contacting a hydroxy-terminated polylactone of formula VII with 1,1-carbonyldiimidazole to produce a polylactone acylimidazole.

The acylimidazole is then contacted with a suitable polyamine to afford a polylactone aminocarbamate.

The reaction of the hydroxy-terminated polylactone of formula VII with 1,1-carbonyldiimidazole is typically conducted on an essentially equimolar basis, although excess 1,1-carbonyldiimidazole can be used to increase the yield of the acylimidazole. The reaction may be conducted by contacting the hydroxy-terminated polylactone with 1,1-carbonyldiimidazole at temperatures ranging from about -10° C. to about 200° C., typically in an inert solvent, such as benzene, toluene, dichloromethane, and the like, for about 0.25 to about 50 hours.

A polylactone aminocarbamate is then formed by contacting the polylactone acylimidazole with a suitable polyamine at a temperature ranging from about 0° C. to about 150°C. for about 0.01 to about 24 hours. This reaction may be conducted with or without an inert solvent. Suitable inert solvents include benzene, toluene, dichloromethane, and the like. The molar ratio of polyamine to polylactone acylimidazole will generally range from about 2:1 about 20:1, preferably 5:1 to 10:1. The desired product may be obtained by washing the reaction mixture with water and stripping the mixture, usually under vacuum, to remove any residual solvent.

Fuel compositions

The polylactone aminocarbamates of the present invention are useful as additives in hydrocarbon fuels to prevent and control engine deposits, particularly intake valve deposits. Typically, the desired deposit control will be achieved by operating an internal combustion engine with a fuel composition containing a polylactone aminocarbamate of the present invention. The proper concentration of additive necessary to achieve the desired deposit control varies depending upon the type of fuel employed, the type of engine, and the presence of other fuel additives.

In general, the concentration of the polylactone aminocarbamates of this invention in hydrocarbon fuel will range from about 50 to about 2,500 parts per million (ppm) by weight, preferably from 75 to 1,000 ppm. When other deposit control additives are present, a lesser amount of the present additive may be used. Furthermore, lower concentrations of, for example, 30 to 70 ppm may be preferred when the present additives are employed as carburetor detergents only.

The polylactone aminocarbamates of the present invention may be formulated as a concentrate using an inert stable oleophilic (i.e., dissolves in gasoline) organic solvent boiling in the range of about 150° F. to 400° F. (about 65° C. to 205° C.). Preferably, an aliphatic or an aromatic hydrocarbon solvent is used, such as benzene, toluene, xylene or higher-boiling aromatics or aromatic thinners. Aliphatic alcohols containing about 3 to 8 carbon atoms, such as isopropanol, isobutylcarbinol, n-butanol and the like, in combination with hydrocarbon solvents are also suitable for use with the present additives. In the concentrate, the amount of the additive will be generally range from about 10 to about 70 weight percent, preferably 10 to 50 weight percent, more preferably from 10 to 25 weight percent.

In gasoline fuels, other fuel additives may be employed with the additives of the present invention, including, for example, oxygenates, such as t-butyl methyl ether, antiknock agents, such as methylcyclopentadienyl manganese tricarbonyl, and other dispersants/detergents, such as hydrocarbyl amines, hydrocarbyl poly(oxyalkylene) amines, or succinimides. Additionally, antioxidants, metal deactivators and demulsifiers may be present.

In diesel fuels, other well-known additives can be employed, such as pour point depressants, flow improvers, cetane improvers, and the like.

A fuel-soluble, nonvolatile carrier fluid or oil may also be used with the polylactone aminocarbamates of this invention. The carrier fluid is a chemically inert hydrocarbon-soluble liquid vehicle which substantially increases the nonvolatile residue (NVR), or solvent-free liquid fraction of the fuel additive composition while not overwhelmingly contributing to octane requirement increase. The carrier fluid may be a natural or synthetic oil, such as mineral oil, refined petroleum oils, synthetic polyalkanes and alkenes, including hydrogenated and unhydrogenated polyalphaolefins, and synthetic polyoxyalkylene-derived oils, such as those described, for example, in U.S. Pat. No. 4,191,537 to Lewis and polyesters, such as those described, for example, in U.S. Pat. Nos. 3,756,793 and 5,004,478, and in European Patent Application Nos. 356,726 and 382,159.

These carrier fluids are believed to act as a carrier for the fuel additives of the present invention and to assist in removing and retarding deposits. The carrier fluid may also exhibit synergistic deposit control properties when used in combination with the polylactone aminocarbamates of this invention.

The carrier fluids are typically employed in amounts ranging from about 100 to about 5,000 ppm by weight of the hydrocarbon fuel, preferably from 400 to 3,000 ppm of the fuel. Preferably, the ratio of carrier fluid to deposit control additive will range from about 0.5:1 to about 10:1, more preferably from 2:1 to 5:1, most preferably about 4:1.

When employed in a fuel concentrate, carrier fluids will generally be present in amounts ranging from about 20 to about 60 weight percent, preferably from 30 to 50 weight percent.

EXAMPLES

The following examples are presented to illustrate specific embodiments of the present invention and synthetic preparations thereof and should not be interpreted as limitations upon the scope of the invention.

Example 1

Preparation of Polyisobutyl-4-Nitrobenzoate

4-Nitrobenzoyl chloride (12.7 grams) was combined with 47.6 grams of polyisobutanol (molecular weight average 984, prepared via hydroformylation of Amoco H-100 polyisobutene) and 300 mL of anhydrous toluene. Triethylamine (10.0 mL) and 4-dimethylaminopyridine (4.2 grams) were then added and the resulting mixture heated to reflux under nitrogen for sixteen hours. The reaction was cooled to room temperature and diluted with diethyl ether. The organic layer was washed twice with 1% aqeous hydrochloric acid, twice with aqeous sodium bicarbonate solution, and once with brine. The organic layer was then dried over anhydrous magnesium sulfate, filtered and the solvents removed in vacuo to yield 41.9 grams of a yellow oil. The oil was chromatographed on silica gel, eluting with hexane/ethylacetate/ethanol (9:0.8:0.2) to yield 37.2 grams of the desired product as a light yellow oil. IR (neat) 1725 cm⁻¹, ¹ H NMR (CDCl₃) δ8.3, 8.2 (AB quartet, 4H), 4.35 (t, 2H), 0.6-1.8 (m, 137H).

Example 2

Preparation of Polyisobutyl-4-Aminobenzoate

A solution of 30.75 grams of the product from Example 1 in 220 mL of ethyl acetate containing 3.5 grams of 10% palladium on charcoal was hydrogenated at 35-40 psi for 16 hours on a Parr low-pressure hydrogenator. Catalyst filtration and removal of the solvent in vacuo yielded 29.44 grams of the desired product as a light yellow oil. IR (neat) 1709, 1696 cm⁻¹. ¹ H NMR (CDCl₃) δ7.9 (d, 2H), 6.65 (d, 2H), 4.3 (t, 2H), 4.1 (bs, 2H), 0.6-1.8 (m, 137H).

Example 3

Preparation of ##STR12##

Trimethylaluminum (12.2 mL of a 2.0M solution in toluene) was added to anhydrous dichloromethane (100 mL) via syringe under nitrogen. The solution was cooled to 0° C. and the product from Example 2 dissolved in 100 mL of anhydrous dichloromethane was added dropwise. The reaction was stirred at room temperature for 30 minutes and then cooled back to 0° C. ε-Caprolactone (5.4 mL) was added all at once, the cooling bath was removed and the reaction was stirred at room temperature for sixteen hours. The reaction was quenched with 100 mL of 5% aqueous hydrochloric acid and was extracted three times with dichloromethane. The combined organic layers were dried over anhydrous magnesium sulfate, filtered and the solvents removed in vacuo to yield 30.4 grams of the desired product as a yellow oil.

Example 4

Preparation of ##STR13##

1,1'-Carbonyldiimidazole (7.8 grams) was added to the product from Example 3 (24.3 grams) dissolved in dichloromethane (300 mL). The reaction was stirred under nitrogen at room temperature for 40 minutes and then diluted with dichloromethane (750 mL). Water (750 mL) was added and the mixture was stirred for ten minutes at room temperature. The phases were separated, and the organic phase was washed with water twice more, dried over anhydrous sodium sulfate, filtered and the solvents removed in vacuo to yield 27.7 grams of the desired product as a yellow oil.

Example 5

Preparation of ##STR14##

The product from Example 4 (27.7 grams) dissolved in anhydrous dichloromethane (100 mL) was added dropwise to ethylenediamine (13.6 mL) dissolved in anhydrous dichloromethane (200 mL) under nitrogen at room temperature. The reaction was stirred at room temperature for two hours, diluted with dichloromethane (200 mL), washed twice with water (150 mL), dried over anhydrous sodium sulfate, filtered and the solvents removed in vacuo to yield 25.9 grams of the desired product as a yellow oil. ¹ H NMR (CDCl₃ /D₂ O) δ₋₋ 8.0 (d, 2H), 7.6 (d, 2H),₋₋ 4.3 (t, 2H), 4.0 (t, 2H), 3.2 (m, 2H), 2.8 (t, 2H), 2.4 (t, 2H), 2.3 (t, 2H), 0.6-1.8 (m, 149H).

Example 6

Single-Cylinder Engine Test

The test compounds were blended in gasoline and their deposit reducing capacity determined in an ASTM/CFR single-cylinder engine test. A Waukesha CFR single-cylinder engine was used. Each run was carried out for 15 hours, at the end of which time the intake valve was removed, washed with hexane and weighed. The previously determined weight of the clean valve was subtracted from the weight of the value at the end of the run. The differences between the two weights is the weight of the deposit. A lesser amount of deposit indicates a superior additive. The operating conditions of the test were as follows: water jacket temperature 200° F.; vacuum of 12 in Hg, air-fuel ratio of 12, ignition spark timing of 40° BTC; engine speed is 1800 rpm; the crankcase oil is a commercial 30W oil.

The amount of carbonaceous deposit in milligrams on the intake valves is reported for each of the test compounds in Table I.

                  TABLE I                                                          ______________________________________                                         Single-Cylinder Engine Test Results                                                   Intake Valve Deposit Weight                                                    (in milligrams)                                                         Sample.sup.1                                                                            Run 1         Run 2    Average                                        ______________________________________                                         Base Fuel                                                                               300.1         302.3    301.2                                          Example 5                                                                                16.0          22.6     19.3                                          ______________________________________                                          .sup.1 At 150 parts per million actives (ppma).                          

The base fuel employed in the above single-cylinder engine tests was a regular octane unleaded gasoline containing no fuel detergent. The test compounds were admixed with the base fuel to give a concentration of 150 ppma (parts per million actives).

The data in Table I illustrates the significant reduction in intake valve deposits provided by a polylactone aminocarbamate of the present invention (Example 5) compared to the base fuel. 

What is claimed is:
 1. A fuel-soluble compound of the formula: ##STR15## wherein R₁ is an alkyl group having from 1 to about 100 carbon atoms or an aralkyl or alkaryl group having from 7 to about 100 carbon atoms;R₂ is an alkylene group of about 2 to 5 carbon atoms; A is a polyamine moiety having at least one basic nitrogen atom; x is an integer from 1 to 25; and y is an integer from 0 to
 6. 2. The compound according to claim 1, wherein R₁ is an alkyl group having from 1 to about 100 carbon atoms.
 3. The compound according to claim 2, wherein R₁ is an alkyl group having from about 3 to about 100 carbon atoms.
 4. The compound according to claim 1, wherein R₂ is an alkylene group of about 4 to 5 carbon atoms.
 5. The compound according to claim 4, wherein R₂ is an alkylene group of 5 carbon atoms.
 6. The compound according to claim 1, wherein x is an integer of from 1 to 10, and y is an integer from 0 to
 2. 7. The compound according to claim 1, wherein the polyamine moiety contains from 2 to about 12 amine nitrogen atoms and from 2 to about 40 carbon atoms.
 8. The compound according to claim 7, wherein the polyamine moiety is derived from a polyalkylene polyamine containing from 2 to about 12 amine nitrogen atoms and 2 to about 24 carbon atoms.
 9. The compound according to claim 8, wherein the polyalkylene polyamine has the formula:

    H.sub.2 N--(R.sub.3 --NH).sub.z --H

wherein R₃ is an alkylene group having 2 to about 6 carbon atoms and z is an integer from 1 to
 4. 10. The compound according to claim 9, wherein R₃ is an alkylene group having 2 to 4 carbon atoms.
 11. The compound according to claim 10, wherein the polyalkylene polyamine is ethylene diamine or diethylene triamine.
 12. The compound according to claim 11, wherein the polyalkylene polyamine is ethylene diamine.
 13. A fuel composition comprising a major amount of hydrocarbons boiling in the gasoline or diesel fuel range and an effective deposit-controlling amount of a fuel-soluble compound of the formula: ##STR16## wherein R₁ is an alkyl group having from 1 to about 100 carbon atoms or an aralkyl or alkaryl group having from to about 100 carbon atoms;R₂ is an alkylene group of about 2 to 5 carbon atoms; A is a polyamine moiety having at least one basic nitrogen atom; x is an integer from 1 to 25; and y is an integer from 0 to
 6. 14. The fuel composition according to claim 13, wherein R₁ is an alkyl group having from 1 to about 100 carbon atoms.
 15. The fuel composition according to claim 14, wherein R₁ is an alkyl group having from about 3 to about 100 carbon atoms.
 16. The fuel composition according to claim 13, wherein R₂ is an alkylene group of about 4 to 5 carbon atoms.
 17. The fuel composition according to claim 16, wherein R₂ is an alkylene group of 5 carbon atoms.
 18. The fuel composition according to claim 13, wherein x is an integer of from 1 to 10, and y is an integer from 0 to
 2. 19. The fuel composition according to claim 13, wherein the polyamine moiety contains from 2 to about 12 amine nitrogen atoms and from 2 to about 40 carbon atoms.
 20. The fuel composition according to claim 19, wherein the polyamine moiety is derived from a polyalkylene polyamine containing from 2 to about 12 amine nitrogen atoms and 2 to about 24 carbon atoms.
 21. The fuel composition according to claim 20, wherein the polyalkylene polyamine has the formula:

    H.sub.2 N--(R.sub.3 --NH).sub.z --H

Wherein R₃ is an alkylene group having 2 to about 6 carbon atoms and z is an integer from 1 to
 4. 22. The fuel composition according to claim 21, wherein R₃ is an alkylene group having 2 to 4 carbon atoms.
 23. The fuel composition according to claim 22, wherein the polyalkylene polyamine is ethylene diamine or diethylene triamine.
 24. The fuel composition according to claim 23, wherein the polyalkylene polyamine is ethylene diamine.
 25. The fuel composition according to claim 13, wherein the composition contains about 50 to about 2500 parts per million by weight of the fuel-soluble compound.
 26. The fuel composition according to claim 13, wherein the composition further contains about 100 to about 5000 parts per million by weight of a fuel-soluble, nonvolatile carrier fluid.
 27. A fuel concentrate comprising an inert stable oleophilic organic solvent boiling in the range of from about 150° F. to 400° F. and from about 10 to about 70 weight percent of a fuel-soluble compound of the formula: ##STR17## wherein R₁ is an alkyl group having from 1 to about 100 carbon atoms or an aralkyl or alkaryl group having from 7 to about 100 carbon atoms;R₂ is an alkylene group of about 2 to 5 carbon atoms; A is a polyamine moiety having at least one basic nitrogen atom; x is an integer from 1 to 25; and y is an integer from 0 to
 6. 28. The fuel concentrate according to claim 27, wherein R₁ is an alkyl group having from 1 to about 100 carbon atoms.
 29. The fuel concentrate according to claim 28, wherein R₁ is an alkyl group having from about 3 to about 100 carbon atoms.
 30. The fuel concentrate according to claim 27, wherein R₂ is an alkylene group of about 4 to 5 carbon atoms.
 31. The fuel concentrate according to claim 30, wherein R₂ is an alkylene group of 5 carbon atoms.
 32. The fuel concentrate according to claim 27, wherein x is an integer of from 1 to 10, and y is an integer from 0 to
 2. 33. The fuel concentrate according to claim 27, wherein the polyamine moiety contains from 2 to about 12 amine nitrogen atoms and from 2 to about 40 carbon atoms.
 34. The fuel concentrate according to claim 33, wherein the polyamine moiety is derived from a polyalkylene polyamine containing from 2 to about 12 amine nitrogen atoms and 2 to about 24 carbon atoms.
 35. The fuel concentrate according to claim 34, wherein the polyalkylene polyamine has the formula:

    H.sub.2 N--(R.sub.3 --NH).sub.z --H

wherein R₃ is an alkylene group having 2 to about 6 carbon atoms and z is an integer from 1 to
 4. 36. The fuel concentrate according to claim 35, wherein R₃ is an alkylene group having 2 to 4 carbon atoms.
 37. The fuel concentrate according to claim 36, wherein the polyalkylene polyamine is ethylene diamine or diethylene triamine.
 38. The fuel concentrate according to claim 37, wherein the polyalkylene polyamine is ethylene diamine.
 39. The fuel concentrate according to claim 27, wherein the fuel concentrate further contains about 20 to about 60 weight percent of a fuel-soluble, nonvolatile carrier fluid. 